The class-action lawsuit has been filed, but Consumer Reports claims Fitbit’s trackers are accurate and their heart monitoring feature works perfectly. There is little doubt that Fitbit has likely climbed up the ranks to the peak of fitness trackers. Their devices have become a force to reckon with in terms of competition, one that Apple is currently facing.

However, on January 5th, customers from several states filed a class-action lawsuit against the company. The accusations? The users stated that their devices had “a very significant margin” of error, especially during intense workouts. Particularly, the problems were found in Fitbit Charge HR and Fitbit Surge. This did not only question the quality of the products, but implicitly affected the health assessment of the users.

Fitbit’s shares dropped in consequence

According to the lawsuit, when placed against manual measuring of heart rate or other equipment, Fitbit’s gadgets were off by an average of 24 beats per minute. In the most severe cases, usually during intense exercise, the margin of error climbed up to a worrying 75 beats per minute. In consequence, Fitbit’s share dropped around 20% in that week at the beginning of the year.

However, the company stood firmly behind their PurePulse technology.

Now, Consumer Reports seems to be backing the fitness trackers. In order to properly test the wrist wearables, they recruited two volunteers, one male and one female. For better terms of comparison on the efficiency of Fitbit Charge HR and Fitbit Surge, the participants were strapped with a Polar H7 device on their chest that monitors heart rate. The product’s quality has been well proven, though it suffers in popularity due to the discomfort it may cause the user.

The tests were underway and participants were monitored in four different phases. At rest, at a walking pace where they recorded 110 beats per minute (bpm), at a jogging pace with 130 bmp, and at a fast running with 150 bpm. And just to be sure, they conducted the tests once more.

A mere 3 bmp margin of error

According to their results, both the Fitbit Charge HR and Fibit Surge work just fine. The margin of error was insignificant, of just 3 bmp, between devices. That is nowhere near the alleged differences that were spotted by the accusing party. The only slight problem encountered is when the female volunteer wore the Charge HR on her wrist. The margin there was of 6 bmp, a slight but nonetheless mention-worthy difference.

However, the gadget arrives with the advice that it can be worn a few inches higher up the forearm for more accurate results. When that was tested, the heart rate tracking improved. But in this day and age, not everyone reads the instruction manual.